Bioactivity of azadirachtin and its field efficiency against Spodoptera litura
印楝素乳油对斜纹夜蛾的生物活性及田间防效研究

In this paper, the effects of varying concentration azadirachtin on tobacco cutworm Spodoptera litura were investigated in both laboratory and field. The results showed that azadirachtin exhibited a wide range of bioactivities, including anti-feeding, growth inhibition, larval toxicity, and oviposition deterrent. This compound could significantly reduce pupal weight and pupation and eclosion rates. After treated with 12 microl x L(-1) azadirachtin for 5 and 7 days, the third instar larvae only weighted 36.8% and 14.5% of the untreated ones, and their development took approximately 6 days longer, with a 27.79% pupation rate and a 37.23% emergence rate, significantly lower than the control by 85.66% and 82.11%, respectively. Azadirachtin was more efficient for the low instar larva than the old ones. Field experiments confirmed that after 7 days application, azadirachtin could effectively control Spodoptera litura, being more efficient than the chemistry pesticide, 10% Chu-Jin SC.